The present invention is drawn to a process for disassembling a brazed structure and, more particularly, a brazed structure comprising a hollow component having a closure component bonded thereto by a metallic brazing alloy for closing off an end of the hollow component.
Brazing processes are known in the prior art for forming a metallic bond between two metal surfaces. Aircraft gas turbine engines rely heavily on a number of brazing processes. For example, open-face honeycomb structures, or air seals, are brazed for use in high temperature heat-resistance applications on lightweight aircraft engines. The unique characteristic of such air seal structures is that the core structure provides an effective seal for a stream of hot gas.
Several methods are known in the prior art for chemically separating brazed components. These approaches utilize leaching and stripping solutions. These methods are generally difficult to control and often lead to damage to the base metal. Such methods are disclosed, for example, in U.S. Pat. Nos. 4,274,908, 4,302,246, and 4,324,626.
U.S. Pat. Nos. 5,439,637 and 5,871,139 disclose processes for removing metallic brazing alloys from brazed joints by packing the joints with metallic powders and the like.
Naturally, it would be highly desirable to provide a process for removing metallic brazing alloy from honeycomb structures as defined above without the requirement of chemical acid stripping and the like.
The foregoing object is achieved by way of the present invention which provides a process for disassembling a brazed structure (for example open face honeycomb structures which are static parts and act as sealing surfaces in jet engines) comprising a hollow component having at least one hollow element and closure component bonded thereto by a metallic brazing alloy for closing off an end of the at least one hollow element wherein the at least one hollow element and closure component define an open faced cell. The process of the present invention comprises the steps of locating in the cell a wire transport material, covering the open faced cell with a metal wire fiber material which penetrates the cell and contacts the wire transport material, and heating the hollow component to sufficient temperature wherein the metallic brazing alloy flows through the wire transport material and onto the metal wire fiber material. In accordance with the present invention, the wire transport material comprises a packing of metal wires of various shapes and sizes which form capillary passages at the interstitial locations between the wires.
Further objects and advantages of the present invention will appear hereinbelow.